1. Field of the Invention
The invention relates to a belt band conveyor, particularly a curved belt conveyor, having an endless transport belt that is guided over deflection rollers. There is a guide element that projects beyond the belt plane and which can be handled separately before it is attached to the transport belt, and which moves along as the transport belt moves. The guide element has guide surfaces that extend in the transport direction of the transport belt. Running surfaces that are inclined relative to the belt plane roll off from rotating guide rollers on the guide surfaces, so that transverse forces that occur crosswise to the transport direction of the transport belt are compensated.
2. The Prior Art
A curved belt conveyor is described in German Patent No. DE 42 13 035 A1. This document describes a circulating endless transport belt which is connected with an edge bead that runs along its outside edge, is continuous, is inseparably connected with it, and circulates along with it. Several guide rollers are elastically pressed against this flank, which points towards the center of the curve, in order to compensate the longitudinal and traverse forces that occur as a result of the curve progression, even in the case of a severely distorted curve, and in the case of significant level differences between the deflection rollers at the end, with low friction wear.
A similar curved belt conveyor having a transport belt that is deflected via cone-shaped support rollers, which has a continuous, co-circulating, bead-shaped edge strip, is described in German Patent No. DE 38 26 953 A1. The edge strip, again, is guided between guide rollers that have inclined running surfaces, in order to compensate the centripetal forces that occur during operation.
A similar belt band conveyor is described in DE 198 54 327 A1. There, a toothed belt component of a continuous toothed belt that circulates with the transport belt is provided to transfer the force of the drive forces from a gear crown to the transport belt. The toothed belt component is connected with the transport belt by bonding, vulcanizing, or gluing. The toothed belt component has a bead strip on its ends that point radially inward, in each instance, which is continuous over the length of the transport belt. Again, inclined running surfaces of guide rollers engage on the bead, in order to be able to absorb the forces directed to the inside radius of belt curves, and in order to achieve secure guidance of the transport belt in this manner.
A further development of the belt band conveyor described above is disclosed in German Patent No. DE 199 53 691 A1, which relates to a belt tensioning device. There, a continuous toothed belt is attached to the bottom of the transport belt, moving with it, and an endless profile that lies opposite is attached to the top of the belt. The profile has an elevation that faces away from the edge region of the transport belt, which again contacts guide rollers. In order to secure the position of the transport belt when the belt starts up under stress, and in order to prevent the teeth of the gear wheel of the drive roller and the teeth of the toothed belt from becoming disengaged, several ball bearings are additionally provided, which contact the profile at the top of the transport belt.
Another system of a curved belt conveyor is described in German Patent No. DE 198 05 204 A1. There, a continuous holder strip is attached on the inside of a circulating transport belt, via the outside radius of the holder strip. Slide sleeves that can rotate about axles of rotation arranged perpendicular to the transport belt plane are attached to the holder strip; they are guided in guide grooves of guide rails, with a positive lock.
All of the aforementioned belt band conveyors have the disadvantage that the lifetime of the guide strips is very short. At high speeds, such guide strips fail after a relatively short period of use. In the case of wear-related damage or complete failure of the guide strips, the entire transport belt must be replaced. This is time-consuming and expensive.
Other embodiments relate to curved belt conveyors in which guide rollers that circulate with the belt are attached, and are guided in locally fixed guides. Such a curved belt conveyor is described in European Patent No. EP 0 880 462 B1. Several co-circulating rollers are provided on the endless transport belt of this conveyor, to guide it and to compensate radial forces that are directed toward the inside of the curve; the axles of rotation of these rollers are attached to the transport belt by way of attachment means that project through openings in the transport belt. As the transport belt circulates, the running surfaces of the co-circulating rollers run along either only vertical or vertical and horizontal stationary guide surfaces of a support frame.
Similar curved belt conveyors are described in U.S. Pat. No. 5,332,082 and NL-A-8702617. In the case of all these curved belt band conveyors, however, permanent excess stress in the region of the roller attachment to the belt can occur, in connection with the risk of canting and/or tearing in this region, so that these belt band conveyors cannot guarantee long life. However, a long life of the belt is particularly important, particularly in the case of belt curves, because as a rule, the belt is the most expensive element, and the replacement part is accordingly expensive. Another disadvantage in the case of these belt band conveyors is the great noise development, particularly at high circulation speeds.